This invention relates generally to battery charging devices, and more particularly to a battery charger having the capability of charging at least two batteries at two independent charging rates while maintaining a low peak power consumption level.
Battery chargers which charge two or more rechargeable batteries at the same time are well known and commercially available. Additionally, batteries employing auxiliary cells which require a different charge level than the basic cells of the battery must employ a battery charger which charges the auxiliary cells separately at a separate rate of charge. (See Jasinski, "Chargers for Batteries with Auxiliary Cells", Motorola Technical Developments, Vol. 8, October 1988, pp. 107-8). Furthermore, charging batteries with battery chargers employing different charging rates has been disclosed in U.S. Pat. Nos. 4,006,396 and 4,727,306 and in U.S. patent application Ser. No. 341,778, "Method and Apparatus for Determining Battery Type and Modifying Operating Characteristics", filed on Apr. 21, 1989 in behalf of Johnson et al.
Each of the earlier battery chargers, however, simultaneously charge all batteries inserted into the charger at a high rate of charge. If size and weight are factors in the design of a battery charger, it would be desirable to reduce the volume of the charging circuitry while improving the efficiency. Also, if each battery were not simultaneously charged, it would be desirable to provide a priority of charging so that the user would know which battery would be charged first.